ABSTRACT

Efficacy and outcome of all magnetorheological finishing (MRF) processes depend on rheological properties of the magnetorheological (MR) fluid which consists of carbonyl iron particles (CIPs), abrasives and carrier fluid. Thus it is important to understand particle distribution in MR fluid which affects the rheological properties of the fluid under the influence of the applied magnetic field and hence the finishing process. A hexagonal microstructure model of MR fluid is considered and a modified model of abrasive doped MR fluid is developed for generation of estimation curve based on ratio of size of abrasive particles to CIP. MR fluid was prepared based on these estimated values and was used for finishing of N-BK7 glass on Ball End MRF (BEMRF) machine. MR fluid with four different abrasive size to CIP size ratios were prepared with CIP volume fraction of 32.9% and Cerium Oxide particles volume fraction of 12.5% with 54.6% water. Another experiment with size of cerium oxide particles to size of CIP ratio of 0.761 is taken for four different concentrations of abrasives and CIPs. Best results with 79.85% improvement in roughness and 0.672 µg/minute MRR were obtained for fluid prepared as per proposed estimation curve for efficient finishing process.

摘要

所有磁流变精加工（MRF）过程的功效和结果取决于磁流变（MR）流体的流变特性，该磁流变（MR）流体由羰基铁颗粒（CIP），磨料和载体流体组成。因此，重要的是要了解MR流体中的颗粒分布，该分布会在施加的磁场和最终加工过程的影响下影响流体的流变性。考虑了MR流体的六角形微观结构模型，并开发了一种掺杂磨料的MR流体模型，用于基于磨料颗粒尺寸与CIP的比率生成估算曲线。基于这些估计值制备MR流体，并将其用于在Ball End MRF（BEMRF）机器上精加工N-BK7玻璃。制备具有四种不同磨料尺寸与CIP尺寸比的MR流体，其中CIP体积分数为32.9％，氧化铈颗粒体积分数为12.5％，用水为54.6％。对于四种不同浓度的磨料和CIP，进行了另一项实验，即氧化铈颗粒的尺寸与CIP的尺寸之比为0.761。根据建议的有效精加工工艺估计曲线制备的流体，可获得最佳结果，粗糙度提高了79.85％，MRR为0.672 µg /分钟。